I use the Suunto Race S, really good watch especially for running, cycling and in the gym. Its more a sportwatch with a few handy features but not a real smartwatch. The sleeping and HR are pretty good for me.
If you like open source projects, have a look at the banglejs. It can do most of what other smart watches do, but privacy friendly, and with a runtime of about a week per charge. However, it is less flashy/shiny and a bit more experimental than the Apple watch and the like.